Endoluminal prosthesis

ABSTRACT

An endoluminal prosthesis is provided that includes a tubular graft and an expandable annular support structure for use in a body lumen through which body fluids flow. The annular support structure is coupled to the tubular graft where it is to be sealingly engaged with the inner wall of a body lumen so that the graft and support structure, in combination, provide an improved seal. An embodiment according to the invention provides an annular structure with longitudinally staggered apices providing multiple levels of contact with the inner body lumen wall to provide a seal at multiple levels along the length of the prosthesis. One embodiment relates to tubular grafts for endoluminal placement within blood vessels for the treatment of abdominal and other aneurysms.

FIELD OF THE INVENTION

The present invention relates to tubular prostheses such as grafts andendoluminal prostheses including, for example, stent-grafts and aneurysmexclusion devices, and methods for placement of such grafts andendoluminal structures. More particularly, the present invention relatesto an improved a tubular graft and support structure for placementwithin or in place of a body lumen.

BACKGROUND OF THE INVENTION

A wide range of medical treatments have been previously developed using“endoluminal prostheses,” which terms are herein intended to meanmedical devices which are adapted for temporary or permanentimplantation within a body lumen, including both naturally occurring orartificially made lumens. Examples of lumens in which endoluminalprostheses may be implanted include, without limitation: arteries suchas those located within coronary, mesentery, peripheral, or cerebralvasculature; veins; gastrointestinal tract; biliary tract; urethra;trachea; hepatic shunts; and fallopian tubes. Various types ofendoluminal prostheses have also been developed, each providing auniquely beneficial structure to modify the mechanics of the targetedluminal wall.

A number of vascular devices have been developed for replacing,supplementing or excluding portions of blood vessels. These vasculargrafts may include but are not limited to endoluminal vascularprostheses and stent grafts, for example, aneurysm exclusion devicessuch as abdominal aortic aneurysm (“AAA”) devices that are used toexclude aneurysms and provide a prosthetic lumen for the flow of blood.

One very significant use for endoluminal or vascular prostheses is intreating aneurysms. Vascular aneurysms are the result of abnormaldilation of a blood vessel, usually resulting from disease or a geneticpredisposition which can weaken the arterial wall and allow it toexpand. While aneurysms can occur in any blood vessel, most occur in theaorta and peripheral arteries, with the majority of aneurysms occurringin the abdominal aorta. Typically an abdominal aneurysm will begin belowthe renal arteries and may extend into one or both of the iliacarteries.

Aneurysms, especially abdominal aortic aneurysms, have been mostcommonly treated in open surgery procedures where the diseased vesselsegment is bypassed and repaired with an artificial vascular graft.While considered to be an effective surgical technique in view of thealternative of a fatal ruptured abdominal aortic aneurysm, the opensurgical technique suffers from a number of disadvantages. The surgicalprocedure is complex and requires long hospital stays due to seriouscomplications and long recovery times and has high mortality rates. Inorder to reduce the mortality rates, complications and duration ofhospital stays, less invasive devices and techniques have beendeveloped. The improved devices include tubular prostheses that providea lumen or lumens for blood flow while excluding blood flow to theaneurysm site. They are introduced into the blood vessel using acatheter in a less or minimally invasive technique. Although frequentlyreferred to as stent-grafts, these devices differ from covered stents inthat they are not used to mechanically prop open natural blood vessels.Rather, they are used to secure an artificial lumen in a sealingengagement with the vessel wall without further opening the naturalblood vessel that is already abnormally dilated.

Typically these endoluminal prostheses or stent grafts are constructedof graft materials such as woven polymer materials (e.g., Dacron,) orpolytetrafluoroethylene (“PTFE”) and a support structure. Thestent-grafts typically have graft material secured onto the innerdiameter or outer diameter of a support structure that supports thegraft material and/or holds it in place against a luminal wall. Theprostheses are typically secured to a vessel wall above and below theaneurysm site with at least one attached expandable annular springmember that provides sufficient radial force so that the prosthesisengages the inner lumen wall of the body lumen to seal the prostheticlumen from the aneurysm. In some devices, a radially expandable memberpartially extends proximally in an axial direction from the graftmaterial. The ring member is substantially uncovered, i.e., has openingsthrough which blood may flow and is therefore useful in placing thedevice at or near the junction of other vasculature, e.g., at or nearthe renal artery where a stent graft is being used to exclude anabdominal aortic aneurysm. When the expandable member must be placednear the renal artery, for example, such an axially extending ringmember may be used so that blood may flow through openings in theexpandable member so that the renal arteries are not occluded. In otherdevices, other mechanisms have also been used to engage the vessel wallssuch as, for example, forcibly expandable members or hook like membersthat puncture the vessel wall. In some devices where attached expandablering members are used, a support bar attaches the ring members toprovide columnar support along the length of the bar.

One of the characteristics desired to prevent collapse of the stentgraft is columnar strength. However, the features that provide columnarstrength may also reduce device flexibility that permits sealingplacement of the device within a tortuous vessel, such as, e.g., adiseased iliac vessel. Further, the devices are subject to cyclicalloading and other stresses. Accordingly it would be desirable to providea device structure having desired loading characteristics, withsufficient columnar strength, while maintaining sufficient flexibilityto allow placement and sealing of the prosthesis within a tortuousvessel.

Additionally, to provide catheter access to the site and make itmaneuverable through the tortuous or narrowed diseased vessels, it isdesirable to provide a stent graft with a high degree of radialcompressibility. Therefore, it is desirable to provide an endoluminaltubular graft that has sufficient strength and loading characteristicswhile maintaining flexibility and radial compressibility into fordelivery from a relatively small diameter delivery catheter.

Further, it is important for the aneurysm exclusion device tosufficiently seal against the vessel wall to prevent blood from enteringthe aneurysm site as it flows through the artificial lumen. Accordingly,it would be desirable to provide an improved seal, especially at theproximal end of the prosthesis.

SUMMARY OF THE INVENTION

An embodiment according to the present invention provides an improvedendoluminal prosthesis having a tubular graft and a support structureattached to the tubular graft and configured in a manner that providescolumnar strength while providing improved device flexibility, and amaintaining a relatively small pre-deployed, collapsed profile.

An embodiment of the endoluminal prosthesis comprises a tubular memberconstructed of a graft material and at least one annular support member.The tubular graft is formed of a woven polymer fiber for conductingfluid. The tubular member includes, a proximal opening and a distalopening providing a lumen through which body fluids may flow. Theannular support members support the tubular graft and/or maintain thelumen in a conformed, sealing arrangement with the inner wall of a bodylumen.

The annular support members each comprise an annular expandable memberformed by an undulating or sinusoidal patterned wire ring. The patternis formed by a plurality of straight spokes connected by a plurality ofapices (alternating crests and troughs) to form a closed ring with anaxis extending longitudinally therethrough. Preferably the annularsupport members are radially compressible springs biased in a radiallyoutward direction, which when released, bias the prosthesis intoconforming fixed engagement with an interior surface of the vessel.Annular springs are provided particularly where the annular supportmember is used to create a seal between the prosthesis and the innerwall of a body lumen. The annular springs are preferably constructed ofNitinol. Examples of such spring means construction are described, forexample, in U.S. Pat. Nos. 5,713,917 and 5,824,041 incorporated hereinby reference. When used in an aneurysm exclusion device, the spring hassufficient radial spring force and flexibility to conformingly engagethe prosthesis with the body lumen inner wall, to avoid excessiveleakage, and prevent pressurization of the aneurysm, i.e., to provide aleak resistant seal. Although some leakage of blood or other body fluidmay occur into the aneurysm isolated by the prosthesis, an optimal sealwill reduce the chances of aneurysm pressurization and resultingrupture.

The annular support members are attached or mechanically coupled to thegraft material along the tubular graft by attaching overlapping adjacentapices of adjacent support members within the circumferential areasdefined by the support member. The support member may be attached to thegraft by various means, such as, for example, by stitching onto eitherthe inside or outside of the tubular graft. Each of the support membersdefines a corresponding circumferential area of graft material aroundit. In one embodiment, at least one of the apices of an annular supportmember is mechanically coupled to the circumferential graft area of anadjacent annular support member. In an embodiment according to theinvention, at least one of the apices of the annular support member ofthe invention extends axially beyond the other apices of that annularsupport member. In this embodiment, the longer crest(s) and/or trough(s)extend into and are attached to the circumferential graft area of anadjacent annular member. The overlap on the graft thus provides columnarstrength along the length of the graft from one support structurethrough the graft and to the next support structure. The overlappingstructure also prevents collapse of the graft between supportstructures. Further, providing fewer overlapping structures allowsgreater radial compressibility of the prosthesis.

In one embodiment according to the invention, the apices, or crests andtroughs of at least one support structure overlap lengthwise (i.e., withrespect to the length or axis of the prosthesis) an apex of an adjacentsupport structure. Such an apex is offset from adjacent apices of theadjacent support structure about the circumferential area of theadjacent support structure. The troughs of a support structure arestaggered about the circumference from the crests of an adjacent supportstructure so that the support structures do not physically touch. In oneembodiment, longer crests or longer troughs of each of the supportmembers are substantially aligned with the other longer crests or longertroughs of adjacent support structures, respectively, to provide columnstrength along a desired length of the prosthesis.

In one embodiment, the support structure is formed of a series ofconnected M-shaped patterns where the troughs are alternatingly long andshort. An adjacent support structure is formed of a series ofalternating upside down M-shaped patterns where the peaks arealternatingly long and short. The longer troughs of the first supportstructure are generally axially aligned with the shorter peaks of theadjacent support structure while the shorter troughs of the firstsupport structure are generally axially aligned with the longer peaks ofthe adjacent support structure. The adjacent longer troughs and longercrests of support structures adjacent to each other are thus staggeredcircumferentially from each other so that the adjacent longer troughs ofa first annular support structure do not physically overlap with theadjacent longer crests of an adjacent second annular support structure.

An embodiment according to the present invention provides such a tubulargraft and improved support structure for endoluminal placement within ablood vessel for the treatment of abdominal and other aneurysms. In thisembodiment, the endoluminal prosthesis is an aneurysm exclusion deviceforming a lumen for the flow of body fluids excluding the flow at theaneurysm site. The aneurysm exclusion device may be used for example, toexclude an aneurysm in the aorta, such as in the abdominal aorta or inthe thoracic region. In an abdominal aorta, the prosthesis may bebifurcated.

The present invention in the embodiment of an Abdominal Aortic Aneurysm(“AAA”) device, the prosthesis is able withstand the loads appliedduring deployment and the cyclical loading in the body for a reasonableduration and provides sealing attachment of the annular supportstructure to the inner wall of the body lumen.

Another aspect of the invention provides an annular support member withsealing points at multiple levels or different heights around theproximal portion of the prosthesis with or without longitudinal overlap.The annular support member sewn on to the tubular graft, comprises anundulating or sinusoidal patterned wire ring. The pattern is formed by aplurality of straight spokes connected by a plurality of apices(alternating crests and troughs) to form a closed ring with an axisextending longitudinally therethrough. The crests are preferably coupledto the proximal end of the graft material while the troughs are providedhaving several different lengths with respect to the axis of the supportmember, or the length of the tubular graft. Thus in addition to radiallybiasing the edge of the fabric and equidistant points below the edge,multiple levels for radially biased sealing points are provided. This isparticularly useful in providing greater device conformity with theinner wall of a lumen while maintaining a relatively low device profilewhen it is radially compressed for delivery. One embodiment according tothis aspect of the invention is a support structure is formed of aseries of connected M-shaped patterns where the troughs arealternatingly long and short. An adjacent support structure may, forexample, be formed of a series of alternating upside down M-shapedpatterns where the peaks are alternatingly long and short, with thelonger troughs of the first support structure generally axially alignedwith the shorter peaks of the adjacent support structure and the shortertroughs of the first support structure generally axially aligned withthe longer peaks of the adjacent support structure. Alternatively the Mshaped patterns may be right side up or a combination of upside down andright side up.

The endoluminal prosthesis may be in the form of either a straightsingle-limb tubular member or a generally Y-shaped bifurcated tubularmember having a trunk joining at a graft junction with a pair of laterallimbs, namely an ipsilateral limb and a contralateral limb. In abifurcated prosthesis, the proximal portion of the prosthesis comprisesa trunk with a proximal opening and the distal portion is branched intoat least two branches with distal openings. Thus body fluids may flowfrom the proximal opening through the distal openings of the branches.Preferably the ipsilateral limb is longer so that when deployed, itextends into the common iliac. A single limb extension member isprovided having a mating portion for engaging and sealing with a laterallimb of a bifurcated member and a leg (whose length may vary as selectedto mate with a particular patient's anatomy) extending coaxially from adistal end of the mating portion. In one embodiment according to theinvention, the improved annular support members are located on theproximal portion of the prosthesis. In another embodiment according tothe invention, the annular support members are located on at least oneof the iliac portions to provide increased flexibility when deployed ina tortuous vessel.

The compressed profile of the prosthesis is sufficiently low to allowthe endoluminal graft to be placed into the vasculature using a lowprofile delivery catheter. The prosthesis can be placed within adiseased vessel via deployment means at the location of an aneurysm.Various means for deployment of the devices are well known in the artand may be found for example is U.S. Pat. Nos. 5,713,917 and 5,824,041,which are incorporated herein by reference. In general, the endoluminalprosthesis is radially compressed and loaded into a catheter. Theaneurysm site is located using an imaging technique such as fluoroscopyand is guided through a femoral iliac artery with the use of a guidewire to the aneurysm site. Once appropriately located, the sheath on thecatheter covering the tubular graft is retracted, thus allowing theannular springs to expand and attach or engage the tubular member to theinner wall of the body lumen. The iliac extension is also loaded into acatheter and is then located into the main body of the stent graft andwithin the iliac vessel where it is deployed. When deployed, the iliacextension is engaged using annular springs proximally within the innerlumen of the main body and distally with the inner wall of the iliacvessel.

These and further aspects of the invention are exemplified and in thedetailed description of embodiments according to the invention describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational perspective view of a first embodiment of anannular support member of a support structure of an endoluminalprosthesis according to an embodiment of the invention.

FIG. 2 is a perspective view of the annular support member of FIG. 1sewn on to graft material forming a tubular member.

FIG. 3 is an elevational perspective view of a second embodiment of anannular support member of a support structure of an endoluminalprosthesis according to an embodiment of the invention.

FIG. 4 is a perspective view of the annular support member of FIG. 3sewn on to graft material forming a tubular member, in particular at theproximal end of such a tubular member.

FIG. 5 is an elevational view showing a bifurcated graft main body in anexpanded condition using a plurality of annular support membersillustrated in FIGS. 1 and 3.

FIG. 6A is an enlarged perspective view of an iliac portion of theprosthesis main body shown in FIG. 5.

FIG. 6B is an enlarged view of a portion of FIG. 6A.

FIG. 6C is the enlarged portion of FIG. 6B in which

FIG. 6D is the enlarged portion of FIG. 6B in which

FIG. 6E is the enlarged portion of FIG. 6B in which

FIG. 6F is the enlarged portion of FIG. 6B in which

FIG. 7 is an enlarged perspective view of the proximal portion of theprosthesis main body shown in FIG. 5

FIG. 8A is an elevational, partial cutaway view showing the bifurcatedgraft main body shown in FIG. 4 with an iliac extension fully deployedwithin an aorta and lateral iliac vessels of a patient having anabdominal aortic aneurysm.

FIG. 8B is an enlarged elevational view of a portion of the prosthesisin FIG. 8A illustrating the connection of the iliac extension to theshort leg of the main body in which the proximal support structure ofthe extension is shown in phantom.

DETAILED DESCRIPTION

FIGS. 1-8B illustrate various embodiments of the support structures andendoluminal prostheses according to the present invention. Although anendoluminal prosthesis according to the invention may be used in anybody lumen that conducts body fluid, it is described herein withreference to treatment of an aortic aneurysm, in particular in theabdomen of a patient.

FIG. 1 illustrates a first embodiment of an annular support member 40used in an endoluminal prosthesis of an embodiment according to theinvention. The annular member 40 comprises five connected V-shapedpatterns in a cylindrical undulating ring (undulating member or straightspokes coupled at apices). In forming this pattern, the annular member40 comprises straight spokes 43 connected by rounded alternating crests41 and troughs 42 encircling a central axis 44 to provide a continuousring. Of the crests 41 and troughs 42 there is at least one longer crest141 and at least one adjacent longer trough 142, each formed so that thelonger crest 141 and longer trough 142 extend a greater distance axiallyfrom the middle circumference 45 (FIG. 2) of the annular member 40, thanthe other crests 41 and troughs 42.

As illustrated in FIG. 2, the annular support member 40 is shownattached to tubular graft material 24 of a prosthesis. The longer crest141 defines an upper circumference 33 generally perpendicular to thecentral axis 44 and the longer trough 142 defines a lower circumference34 generally perpendicular to the central axis 44. The uppercircumference 33 and lower circumference 34 define a circumferentialarea (band) 35 of graft material between the longer crest 141 and thelonger trough 142 of the annular member 40.

FIG. 3 illustrates another embodiment of an annular support member 50used in the endoluminal prosthesis 20 of an embodiment according to theinvention. The annular support member 50 comprises five connectedM-shaped portions 56 in a cylindrical undulating ring. In forming thispattern, the annular member 50 comprises straight spokes 53 connected byrounded alternating crests 51 and troughs 52 encircling a central axis57 to provide a continuous ring. The crests 51 are generally of the sameheight. The troughs 52 comprise alternating shorter troughs 54 andlonger troughs 55 formed so that the longer troughs 55 extend a greaterdistance axially from the middle circumference 58 (middle between theextremes of crest and trough) of the annular member 50 than the shortertroughs 54.

As illustrated in FIG. 4, the annular support member 50 is shownattached to the tubular graft material 24 m. The crests 51 define anupper circumference 61 and the troughs 55 define a lower circumference62 generally perpendicular to the central axis 57. The uppercircumference 61 and lower circumference 62 define a circumferentialarea (band) 63 of graft material 24 m between the crests 51 and thelonger trough 55 of the annular member 50.

The annular support members 40, 50 shown in FIGS. 1 and 2, and FIGS. 3and 4, are preferably a spring members having a predetermined radii andformed of a loop of wire with ends joined together (or a wire ring).Such annular members 40, 50 are preferably constructed of a materialsuch as Nitinol in a superelastic, shape set, annealed condition. Aftera cylindrical undulating ring is formed with the wire, the ends of theNitinol wire are joined end to end inside a connection tube by an inlinecrimp.

FIGS. 5-8B illustrate portions of an endoluminal prosthesis 20 accordingto the present invention in use as an aneurysm exclusion device. Theprosthesis 20 includes a main body portion 25 having an aortic portion26, a long iliac portion 27, a short iliac portion 28 and an iliacextension 29. The prosthesis 20 is constructed of a graft material 24 aformed into a bifurcated tubular member as illustrated. The graftmaterial 24 a is preferably a biocompatible, low-porosity woven fabric,such as a woven polyester. The graft material 24 a is thin-walled sothat is may be compressed into a small diameter catheter, yet capable ofacting as a strong, leak-resistant, fluid conduit when expanded to atubular form.

The prosthesis 20 is further constructed of a plurality of radiallycompressible support members 38 (including support members 50 a-d, 50 tand 40 a-f) for supporting the graft and/or biasing a proximal end 30 ora distal end 31 of the prosthesis into conforming fixed engagement withan interior surface of aorta 10. The annular support members 40, 50illustrated in FIGS. 1 and 3 are examples of the many types of supportmembers 38 that may be used in the prosthesis 20. As described below, inthis embodiment, the configuration of the annular support members 40 ofFIGS. 1 and 2 are used as support members 40 a-f in the distal portionsof the prosthesis 20 and the configuration of annular support members 50of FIGS. 3 and 4 are used as support members 50 a-d in the proximal end30 and an aortic portion 26 of the prosthesis 20. In addition, atransition support member 50 t is used as a transition member betweensupport members 40 a-e, support members 50 a-d.

Support members 38 are attached to the graft material 24 a with sutures39 and are preferably constructed of a material such as Nitinol in asuperelastic condition. At least a proximal support member 50 a biasesproximal end 30 of the prosthesis 20 into conforming engagement with theinternal wall of the aortic blood vessel to provide a substantialsealing engagement therewith, i.e., a leak resistant seal. Preferablythe support structures 38 are spring members, particularly the proximalsupport structure 50 a. In an embodiment according to the invention, thesupport structures 38 are sewn within graft material 24 a using apolyester suture. A preferred stitch pattern may for example, be alocking stitch, e.g., including two generally parallel stitchesextending along opposite sides of the wire, and a cross-over stitcharound the wire for pulling the parallel stitches together to achievetight attachment of graft material 24 to the wire spring. In oneembodiment, the stitching is used to attach the spring along the entirelength of spring wire. In one embodiment, 2-4 stitches per apex areused. The annular support members (40, 50, 40 a-f, 50 a-d, 50 t) aresewn on to the inside or the outside of their respective tubular graftmaterial 24, 24 m or 24 a. Alternatively, the annular support members(40, 50, 40 a-f, 50 a-d, 50 t) may be enclosed within their respectivegraft material 24, 24 m, or 24 a.

As illustrated in FIGS. 5-8B, a central axis 22 generally defines aprosthesis length or a longitudinal direction along the prosthesis. Thesupport structures 38 in the long iliac portion 27 comprise annularmembers 40 a-f constructed in the same manner as annular support member40 as described above with reference to FIG. 1. The support structures38 in the aortic portion comprise annular members 50 a-d constructed inthe same manner as annular support member 50 as described above withreference to FIG. 3 and support member 50 t. The support member 50 t isa transitional member at the distal portion of the aortic portion 26 andthe comprises straight members 53 t connected by crests 51 t and troughs52 t. The troughs 52 t are of the same length along the axis 22, and thecrests 51 t are of the same length along the axis 22 except for twolateral peaks 54 t, one on each side lateral side of the aortic portion26 of the main body 25.

As shown in FIGS. 5, 6A-F, and 8A, the annular members 40 a-f arearranged on the prosthesis 20 so that the protruding apices or longercrests 141 a-e of each annular member 40 a-e respectively are staggeredfrom the adjacent longer troughs 142 b-f of adjacent annular members 40b-f, respectively, in a circumferential direction, while respectivelyoverlapping each other in an axial or longitudinal direction. Theannular support members 40 a-f, sewn on to the graft 24 with sutures 39,provide columnar support with substantial flexibility in the iliacregion to accommodate anatomy which tends to vary from patient topatient and may be extremely tortuous, particularly in highly diseasedanatomy. The annular support members (40 a-f) are coaxially spaced sothat a long trough (141 a-f) and a long crest (142 a-f) of annularsupport members immediately adjacent a particular annular supportmember, extend into a circumferential area defined by such annularmember, similar to the limits of the circumferential area 35 defined byannular support member 50 as shown in FIG. 2. The long troughs 142, 142a-f and crests 141, 141 a-f are sewn into the graft 24, in spacescreated between the troughs and crests of adjacent annular supportmembers. The close approach spacing of the annular support members andthe relatively short length of attached graft material between theseclosely spaced portions of adjacent support members provide relativelysmall accommodation for relative longitudinal movement between adjacentsupport members. The limited flexibility or longitudinal movementprovides columnar support between annular support members along the axisof the endoluminal prosthesis. In the embodiment shown, the stressese.g. the columnar forces, are transmitted along the length of the devicebetween the annular support members, e.g., from an annular supportmember, to the graft material to which they are attached, and then fromthe graft material to the adjacent annular support member. Unlike theprior art, there are no axial or lateral connecting elements betweenadjacent otherwise unconnected annular support members other than thegraft material between the annular support members.

Referring now to FIGS. 6B-6F an enlarged portion of the long ipsalateraliliac portion limb 27 is illustrated in various positions in which thereis some limited axial movement of the support members 40 a and 40 b withrespect to each other. In particular, the spacing of the support members40 a and 40 b with respect to each other permits movement of the supportmembers 40 a and 40 b with respect to each other while the arrangementof the longer peak 141 a of support member 40 a with respect to thelonger trough 142 b of support member 40 b limits such motion. Thelonger trough 142 b and longer peak 141 a are restricted to movementwith respect to each other to parallelograms defined by two pointsselected points on each of the longer through 142 b and longer peak 141a where the distance between the two points on the longer trough 142 bis equal to the distance between the two points on the longer peak 141a. As illustrated in FIG. 6B, the support members 40 a and 40 b are inan initial position in which there is no axial or rotational movement ofthe support members 40 a and 40 b with respect to each other. Thestraight spoke 43 a joining the longer peak 141 a and longer trough 142a of the support member 40 a defines two points 70 a and 71 a on thestraight spoke 43 a. The straight spoke 43 b joining the longer peak 141b and longer trough 142 b of the support member 40 b defines two points70 b and 71 b on the straight spoke 43 b. The distance between thepoints 70 a and 71 a is equal to the distance between points 70 b and 71b. Thus equidistant line segments 70 ab and 71 ab can be drawn betweenthe point 70 a of strut 43 a and point 70 b of strut 43 b, and betweenthe point 71 a of strut 43 a and point 71 b of strut 43 b, respectively.Thus, the line segments defined by points 70 a and 70 b of the strut 43a, and points 71 a and 71 b of strut 43 b, and the line segments 70 aband 71 ab define a parallelogram P1.

As illustrated in FIG. 6C, the longer peak 141 a of the support member40 a is displaced axially away from and rotated with respect to thelonger trough 142 b of support member 40 b. The configuration overlap ofthe longer trough 142 b and longer peak 141 a as described above withreference to FIG. 6A, limits the movement of the longer trough 142 b andlonger peak 141 a with respect to one another to a range of movementgenerally defined by line points 70 a, 71 a, 70 b and 71 b. In thisfigure segments 70 ab′ and 71 ab′ segments of struts 43 a, 43 b definedby points 70 a, 71 a and 70 b, 71 b respectively define, a parallelogramP2. As illustrated in FIG. 6D, the longer peak 141 a of the supportmember 40 a further displaced axially away from and rotated with respectto the longer trough 142 b of support member 40 b. The positioning ofthe longer trough 142 b and longer peak 141 a with respect to each otheris defined by lines 70 ab″ and 71 ab″ and segments of struts 43 a, 43 bdefined by points 70 a, 71 a and 70 b, 71 b respectively formingparallelogram P3.

As illustrated in FIG. 6E, the longer peak 141 a of the support member40 a is displaced axially toward and rotated with respect to the longertrough 142 b of support member 40 b. A range of movement is generallydefined by line segments 70 ab′″, 71 ab′″ and segments of struts 43 a,43 b defined by points 70 a, 71 a and 70 b, 71 b respectively, whichform a parallelogram P4. As illustrated in FIG. 6F, the longer peak 141a of the support member 40 a further displaced axially toward androtated with respect to the longer trough 142 b of support member 40 b.The positioning of the longer trough 142 b and longer peak 141 a withrespect to each other is defined by lines 70 ab″″ and 71 ab″″ andsegments of struts 43 a, 43 b defined by points 70 a, 71 a and 70 b, 71b respectively, forming parallelogram P5. Accordingly, unlike many stentgrafts of the prior art, a connecting element in addition to the supportprovided by annular members sewn on to a tubular graft, is not required.

As shown in FIGS. 5, 7 and 8A, the annular support members 50 a-d and 50t are sewn on to the graft 24 with sutures 39 in a manner that providescolumnar support with substantial flexibility in the aortic region. Theproximal support member 50 a is sewn on the proximal end 30 of theprosthesis 20 with crests 51 a sewn onto edge of the graft material 24and longer troughs 55 a (FIG. 5) extending a greater distance along thelength of the of the prosthesis than the shorter troughs 54 a. Thetroughs 52 a (54 a and 55 a) are thus located at different levels alongthe prosthesis length and thereby provide radial sealing force atdifferent levels to provide greater conforming sealing engagement withthe aorta wall along the length of the prosthesis proximal end 30. Anadjacent support member 50 b is oppositely oriented from the supportmember 50 a, i.e., so that the M-shaped patterns are upside down. Assuch, the crests of the annular member 50 become troughs and the troughsbecome crests (i.e., the crests being toward the proximal end 30). Thecrests 52 b extend in a proximal direction with alternating shortercrests 54 b and longer crests 55 b adjacent the proximal support member50 a. The shorter crests 54 b of support member 50 b are aligned withthe longer troughs 55 a of support member 50 a. The longer crests 55 bof the support member 50 b are aligned with the shorter troughs 54 a ofthe support member 50 a. Longer crests 55 b extend into and are attachedwithin a circumferential area 63 a defined by support member 50 a whilelonger troughs 55 a of support member 50 a extend into and are attachedwithin a circumferential area 63 b defined by support member 50 b.Support members 50 c and 50 d are similarly affixed to the graft 24 a.Support member 50 t is initially in an oval shape prior to being sewn onto the graft 24 a with the long axis of the oval shape from the anteriorto posterior of the prosthesis 20 (FIG. 5 showing an anterior view ofthe prosthesis 20). The longer peaks 54 t extend into the region of thegraft 24 a defined by the adjacent support member 50 d, to providecolumnar support between the annular support members 50 d and 50 t.

Referring to FIG. 8A, the prosthesis 20 is shown in place in anabdominal aorta 10. The aorta 10 is joined by renal arteries 12 and 14at the aorto-renal junction 16. Just below the aorta-renal junction 16is an aneurysm 18, a diseased region where the vessel wall is weakenedand expanded. Below the aneurysm 18, the aorta bifurcates into right andleft iliac vessels 11, 13, respectively. The elongated bifurcatedtubular prosthesis 20 is deployed at the region of aneurysm 18 for thepurpose of relieving blood pressure against the weakened vessel wall, byacting as a fluid conduit through the region of the aneurysm 18. In itsdeployed condition, prosthesis 20 defines a central longitudinal axis 22extending in a direction of blood flow through aorta 10, which generallydefines the length or a longitudinal direction with respect to theprosthesis 20. Proximal annular support member 50 a is designed to exerta radially outward force sufficient to bias graft material 24 of theendoluminal prosthesis 20 into conforming fixed engagement with theinterior surface of aorta 10 above aneurysm 18 and to provide a leakresistant seal between the prosthesis and the inner wall of the aorta10. The other annular support members may also provide radially outwardforces that help seal the proximal end 30 against the wall of the aorta10. The proximal aortic portion 26 of the prosthesis 20 is locatedwithin aorta 10, and is joined to the long ipsalateral iliac portionlimb 27 which is to be located within the right iliac vessel 11. Aseparate single contralateral extension limb 29 is constructed in amanner similar to the long iliac limb portion 27 using annular supportmembers (e.g., 40), e.g., sewn into graft material 24. After deploymentof the main body portion 25, the contralateral extension limb 29 islocated within left iliac vessel 13, and near the graft leg junction 32within the short iliac portion 28. As illustrated in FIG. 8B, theproximal end 29 a of the contralateral extension limb 29 includes aproximal support member 38 n (shown in phantom) biasing the proximal end29 a into conforming fixed engagement with the interior surface of theshort iliac portion 28. The proximal support member 38 n includes longertrough 142 n, but does not include a longer crest.

In the main body portion 25 an open spring 65 is sewn on to the graftmaterial 24 at the proximal end 30 providing uncovered portions or openspring areas 66 beyond the proximal end of the graft material 24. Thusthe open spring 65 may be deployed over the renal arteries 12, 14,without blocking the blood flow through arteries 12, 14. Thus theprosthesis 20 may be situated with proximal end 30 relatively close toaorto-renal junction since openings 66 may be aligned with renalarteries 12 and 14 so as not to block blood flow. To deploy theprosthesis 20, the main body portion 25 of the prosthesis may be loadedinto a catheter. Support members 38 are radially compressed tofacilitate loading insertion of prosthesis 20 within a sheath of acatheter. The main body portion 25 is delivered in a compressed statevia catheter through a surgically accessed femoral artery, to thedesired deployment site. The main body portion 25 is deployed whereinthe support members expand or are expanded into the deployedconfiguration illustrated in FIGS. 5 and 8A-8B.

Using a second catheter, the contralateral limb 29 may be separatelydeployed through a surgically accessed femoral artery after placement ofthe main body portion 25. These and suitable delivery methods andapparatus are generally known in the art and may be used to deliver theprosthesis. This may be done one of several ways. A surgical cut downmay be made to access a femoral iliac artery. The catheter is theninserted into the artery and guided to the aneurysm site usingfluoroscopic imaging where the device is released from the catheter.Where expandable members are used, the members supporting the graft,biased in a radially outward direction, then expand to engage theprosthesis in the vessel against the vessel wall to provide anartificial lumen for the flow of blood. Another technique includespercutaneously accessing the blood vessel for catheter delivery, i.e.,without a surgical cutdown. An example of such a technique is set forthin U.S. Pat. No. 5,713,917, incorporated herein by reference.

Another embodiment according to the invention provides a method ofmanufacturing an endoluminal prosthesis. In the method a tubular graftconstructed of a graft material is provided. The tubular graft definesan opening with an axis therethrough. The method further includesattaching a first annular support member to the graft material, thefirst annular support member comprising a plurality of first apicesextending in a first axial direction with respect to the axis of thetubular graft, wherein at least one of the plurality of first apicesextends axially beyond another of the plurality of first apices. Themethod also includes attaching a second annular support member to thetubular graft adjacent the first annular support member, the secondannular support member comprising a plurality of second apices extendingin a second axial direction opposite to the first axial direction, atleast one of the second apices of the second annular support memberdefining a circumferential area of a portion of the tubular graft aroundthe second annular support member, wherein the at least one of theplurality of first apices of the first annular support member isattached to the tubular graft within the circumferential area.

Another embodiment according to the invention provides another method ofmanufacturing an endoluminal prosthesis. In the method a tubular graftconstructed of a graft material is provided. The tubular graft definesan opening with an axis therethrough. The method further includesattaching a first annular support member to the graft material, thefirst annular support member comprising a plurality of apices coupled bya plurality of spokes and forming a closed ring defining acircumference, wherein the apices comprise alternating crests andtroughs, wherein at least one of the troughs extends axially beyond another of the troughs and wherein the troughs of the annular supportmember comprise a plurality of alternating longer troughs and shortertroughs. A second annular support member is attached to the tubulargraft adjacent the first annular support member, the second annularsupport member comprising a plurality of second spokes coupled by aplurality of second apices to form a second ring, wherein the secondannular support member is attached to the graft material to define acircumferential area of the graft material around the second annularsupport member. Finally, one of the longer troughs of the first supportmember is attached to the graft material within the circumferential areaof the second support member. Another aspect of this method may providealternating second crests and second troughs of the plurality of secondapices of the second annular support member, wherein the second crestscomprise a plurality of alternating longer crests and shorter crests.According to this further aspect, the method may include attaching thelonger troughs of the first annular support member substantially inlongitudinal alignment with the shorter crests of the second annularsupport member; and attaching the shorter troughs of the first annularsupport member in substantially longitudinally aligned with the longercrests of the second annular support member. This method may alsofurther include attaching the first annular support member to the graftmaterial to define a circumferential area of the graft material aroundthe first annular support member; attaching the longer crests of the ofthe second support member within the circumferential area of graftmaterial around the first annular support member; and attaching thelonger troughs of the first support member within the circumferentialarea of graft material around the second annular support member.

Although this detailed description sets forth particular embodimentsaccording to the invention, the present invention contemplates variousother vascular grafts or endoluminal prostheses, especially those inwhich a combination of columnar support, flexibility and/or improvedsealing is desired. For example configurations according to the presentinvention may be used with forcibly expanded coronary and peripheralstents or stent-grafts, covered grafts, vascular grafts, and otheraneurysm exclusion devices. The expandable support structures on variousembodiments of the devices may be, for example, self-expanding, balloonexpandable, or otherwise forcibly expanded.

While the invention has been described with reference to particularembodiments, it will be understood to one skilled in the art thatvariations and modifications may be made in form and detail withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. An endoluminal prosthesis comprising: a tubulargraft having a length and comprising: a graft material, a proximal endhaving a proximal opening, and a distal end having a distal opening,wherein the proximal and distal openings and the graft material form alumen for the flow of body fluids therethrough; an annular supportmember attached to the graft material, but otherwise being unconnectedto another annular support member, said annular support membercomprising a closed ring defining a circumference and an axis extendinglongitudinally therethrough, a plurality of apices coupled by aplurality of spokes, wherein the apices comprise alternating crests andtroughs arranged to hold the graft material in a leak resistant sealingengagement with the inner wall of a body lumen; wherein at least one ofthe troughs extends axially beyond an other of the troughs; wherein thetroughs of the annular support member comprise a plurality ofalternating longer troughs and shorter troughs; wherein said annularsupport member corresponds to a first annular support member and furthercomprising a second annular support member comprising a plurality ofsecond spokes coupled by a plurality of second apices to form a secondring, wherein the second annular support member is attached to the graftmaterial to define a circumferential area of the graft material aroundthe second annular support member, but otherwise being unconnected tosaid first annular support member, and wherein the one of the longertroughs of the first support member is attached to the graft materialwithin the circumferential area of the second support member.
 2. Theendoluminal prosthesis of claim 1 wherein the plurality of second apicesof the second annular support member comprise alternating second crestsand second troughs and wherein the second crests comprise a plurality ofalternating longer crests and shorter crests.
 3. The endoluminalprosthesis of claim 2 wherein the longer troughs of the first annularsupport member are longitudinally aligned with the shorter crests of thesecond annular support member and the shorter troughs of the firstannular support member are longitudinally aligned with the longer crestsof the second annular support member.
 4. The endoluminal prosthesis ofclaim 3 wherein the first annular support member is attached to thegraft material to define a circumferential area of the graft materialaround the first annular support member, and wherein the longer crestsof the of the second support member are attached within thecircumferential area of graft material around the first annular supportmember and the longer troughs of the first support member are attachedwithin the circumferential area of graft material around the secondannular support member.
 5. The endoluminal prosthesis of claim 1 whereinthe prosthesis is an aneurysm exclusion device.
 6. The endoluminalprosthesis of claim 1 wherein the proximal end comprises trunk portionand the distal end is branched into at least two branch portions, eachof the at least two branch portions having a distal opening, the trunkportion and the branch portions forming a lumen for the flow of bodyfluids from the proximal opening through the distal openings of the atleast two branch portions.
 7. The endoluminal prosthesis of claim 1wherein the apices of the crests in the first annular support member arecircumferentially aligned with one another.
 8. An endoluminal prosthesiscomprising: a tubular graft having a length and comprising: a graftmaterial, a proximal end having a proximal opening, and a distal endhaving a distal opening, wherein the proximal and distal openings andthe graft material form a lumen for the flow of body fluidstherethrough; an annular support member attached to the graft material,but otherwise being unconnected to another annular support member, saidannular support member comprising a closed ring defining a circumferenceand an axis extending longitudinally therethrough, a plurality of apicescoupled by a plurality of spokes, wherein the apices comprisealternating crests and troughs arranged to hold the graft material in aleak resistant sealing engagement with the inner wall of a body lumen;wherein at least one of the troughs extends axially beyond an other ofthe troughs; wherein said annular support member corresponds to a firstannular support member and further comprising a second annular supportmember, said second annular support member comprising a closed ringdefining a circumference and an axis extending longitudinallytherethrough, a plurality of apices coupled by a plurality of spokes,wherein the apices comprise alternating crests and troughs; wherein thesecond annular support member is attached to the graft material todefine a circumferential area of the graft material around the secondannular support member, but otherwise is unconnected to said firstannular support member; wherein at least one trough of said firstannular support member extends axially toward said second annularsupport member and axially beyond one of said apices of said secondannular support member.
 9. The endoluminal prosthesis of claim 8 whereinthe troughs of one of the annular support members comprises alternatingshorter troughs and longer troughs.
 10. The endoluminal prosthesis ofclaim 8 wherein the apices of the crests in first annular support memberare circumferentially aligned with one another.